LoPy and custom PCB with L76-L GPS module

We're trying to implement custom PCB with the same module as used in PyTrack - Quectel L76-L.
This question might be a bit off topic but is it necessary to use level shifter to talk to this GPS module through I2C bus ?
We perform i2c.scan() and getting no response from connected and powered module while UART interface works perfectly.

@seb No luck with pull up resistors. There is also garbage when connected on P22/P21.
PyTrack connected to the same pins with the same settings goes smooth.
While connecting our L76-L there is no response on I2C ;-( only garbage response for i2c.scan().